The invention relates to a microwave antenna for simultaneous reception of radiation fields of Nxe2x89xa72 satellites on orbit at azimuthally offset specific positions with respect to one another, whereby the microwave antenna includes radiation components that are divided into N groups, wherein each group is coupled to an input point via a line distribution network [server].
Antennas are known to the art that can be directed sequentially to different satellites by means of an automatic swivel device. The disadvantage in said antennas is, on the one hand, that they do not allow simultaneous reception of satellite signals from different satellites and, on the other hand, they require costly swivel devices.
DE 196 33 147 discloses a multi-focus-reflector antenna, wherein two radiation exciters are easily arranged in a line with the focal point of the parabolic reflector used in such a manner that the signals of two satellites can be received simultaneously without swiveling the antenna. The disadvantage in said antennas is the fact that the radiation exciters cannot be aligned directly in the focal point of the parabolic reflector, whereby the gain of the antenna compared with the reflector size is not optimal.
In order to eliminate said disadvantage, further parabolic antennas are known in the art, wherein a radiation exciter is arranged moveably on a line in front of the reflector, so that with a stationary parabolic reflector several satellites can be intercepted. The disadvantage in this arrangement is the fact that again an expensive positioning device is required for the radiation exciters and the gain of the antenna through the radiation exciters that are not arranged in the focal area is not optimal.
EP 0 825 670 discloses a multifunctional roofing element. Several of such roofing elements can be combined next to each other as a group in place of roofing tiles on the roof of a building for the purpose of receiving satellite signals. The disadvantage in said arrangement is, however, that the antenna, because of the orientation of the building or the concerned roof, is in most cases not suitable for a specific satellite, such that a relatively large number of roofing elements are required in order to afford sufficiently satisfactory reception.
Furthermore, planar antennas are known in the art that allow reception of the satellite signals only from those satellites to which they are directed. Positioning devices for selective directioning to several satellites are known in the are also for use with planar antennas.
The purpose of this invention is to provide a microwave antenna that allows simultaneous reception of several satellites that are azimuthally offset from each other in geostationary orbit without a swivel device.
This purpose is achieved by the invention by a microwave antenna with the characteristics described in claim 1. Said antenna is characterized by the fact that the face provided with radiation elements is sectioned into individual microwave antennas, whereby each microwave antenna exhibits several radiation exciters. Each of said microwave antennas forms a particularly planar or even surface. Said surfaces are arranged at specific angles relative to one another that correspond to the respective azimuthal offset of the satellite to be received. In a simple embodiment, only two groups of radiation elements are present, so that he signals from two satellites can be received. However, more than two satellites can be received simultaneously by the use of the respective number of radiation element groups.
A group of radiation elements can be arranged either next to one another or behind one another. If the groups are arranged behind one another in the direction of radiation then it must be possible for the electromagnetic radiation of the satellite whose signals are to be received by a group of radiation elements that are arranged behind one or several other groups another in the direction of radiation, can pass unimpaired through the interposed groups. If shades such as those described in the exemplar embodiments are used, then they must be arranged in a manner so that the radiation fields can reach the groups in the back through the shade groups situated up front.
The advantage of the microwave antenna described in the invention is that no swivel or positioning device whatsoever is required and it guarantees the maximum gain for each component microwave antenna or flat antenna, whereby a group of radiation elements forms each component microwave antenna.
A further advantage is when at least two radiation element groups are arranged behind one another in the direction of radiation for simultaneous reception from two different polarization directions and/or polarization types.
In a particular embodiment, a dielectric substrate, especially a dielectric foil, carries the circuit distribution nets of several groups. The minimal thickness of the carrier substrate allows this arrangement to be easily bent at required angle corresponding to the azimuthal angle.
In a further particular embodiment the microwave antenna exhibits at least two conductive layers arranged parallel to one another, especially conductive plates, wherein recesses or hollow spaces lying opposite one another are provided such that a dielectric substrate having one or several coupling networks is arranged between each pair of sequential layers, whereby the extremities of each coupling network is oriented towards the recesses or hollow spaces in order to form the radiation elements with same.
The paired conductive layers or plates can herein be fabricated as separate elements or as plates or, however, all conductive layers of the component microwave antennas can be formed by folded conductive plates that are arranged parallel to one another. Herein at least two coupling networks are arranged next to each other between the plates and form the radiation elements together with the plates.
In the last-described embodiment of the inventive microwave antenna at least one spacer element, in particular a dielectric foil with low dielectric number is arranged between each conductive layer or plate and each coupling network.
Thus, in the inventive microwave antenna, several planar antennas are arranged next to each other in a housing, whereby the surface normal of the antennas, in the directed condition of the microwave antenna, face in the direction of the respective correspondent satellite.
When constructing the microwave antenna it must merely be directed towards a satellite. Inasmuch as the microwave antenna is set up for simultaneous reception of signals of two satellites, the alignment with the second satellite can be eliminated, since the two component microwave antennas are already arranged at the correct angle to one another inside the housing.
A further advantage is provided in that only one housing is required for several satellites. If several individual flat antennas with separate housing were arranged next to each other, such an arrangement would require considerably more space when compared to the inventive solution.